Oxidative stress appears to be involved in the pathogenesis of Alzheimer's disease, and most likely involves interactions between A? proteins and polyunsaturated fatty acyl (PUFA) chains. Therefore, we are proposing to (1) determine whether the expression of A? proteins increases the rate of oxidative PUFA metabolism and degradation in brain, and whether the rates differ in disease-prone and disease-resistant regions of brain; (2) test whether A? proteins increase protein modification by lipid oxidation products in general, and whether A? proteins are modified in vivo by the lipid oxidation products that accelerate their aggregation into amyloid fibrils; and (3) test whether specific dietary and pharmacological interventions alter the production of toxic PUFA degradation products in disease-prone brain regions, or the fate of PUFA degradation products in these regions. We will make use of radiolabeled PUFA chains, which will be injected into transgenic mouse models of Alzheimer's disease, as well as quantitative and sequencing mass spectrometry.